A process for manufacturing self-reducing pellets/briquettes from bag house dust mixed with carbon to be used in steelmaking furnaces

ABSTRACT

Bag house dust is combined with a carbon source and shaped into pellets or briquettes and used to recycle valuable metals present in the bag house dust.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of US. Provisional PatentApplication No. 62/504,496 filed May 10, 2017, hereby incorporated byreference in its entirety for all lawful purposes.

FIELD OF THE INVENTION

This invention relates to the fields of steel-making and bag house dustremediation.

BACKGROUND

Steel industries produce significant amount of bag house dust fromelectric arc furnaces (EAFs). EAF dust is formed during steelmakingoperations from metal oxidation and volatilization at high processingtemperatures, and collected as dust in bag houses. Because EAFstypically rely on scrap metal for their charge, the composition of thedust correlates with the chemistry of the metallic charge used, and canvary from one melt to the next. Iron is the primary component of steel,and bag house dust from steel mills consequently includes highconcentrations of iron oxide (40-60%). Zinc oxide and metals includingmanganese, calcium, magnesium, silicon, lead, copper, chromium,aluminum, mercury, and their compounds are also present in bag housedust.

From the global crude steel output of 1.62 billion tons reported by theWorld Steel Association, the international trade body for the iron andsteel industry, about 406 million tons were produced by EAF mills in2015. Approximately 15 to 20 kg of dust is formed per ton ofEAF-produced steel, which corresponds to approximately 3-4 million tonsof EAF bughouse dust produced per year.

Disposal of EAF bughouse dust at landfill disposal sites is becomingincreasingly expensive, as industrial disposal sites become more scarceand remote from the point of origin. Increasing disposal costs and morerestrictive environmental legislation have led to the search foreconomically viable methods to recycle bag house dust. Onsite recyclingof bag house dust in the EAF is limited because its high oxide contenthas a negative impact on the melting process. Successful recycling willreduce disposal costs and extract valuable metal components which wouldotherwise be disposed of. There is a need in the industry for animproved process for recycling of bag house dust.

SUMMARY

The present disclosure provides a method for recycling materials presentin EAF bag house dust. Inventors have found that combining bag housedust with a carbon source in briquettes or pellets provides acomposition that may be used as a feedstock in steel making furnaces,including electric arc and basic oxygen furnaces.

In some embodiments, a solid composition in the form of a briquette orpellet is provided, the solid composition is adapted for use as a feedstock in steel making furnaces and comprises a carbon source and a baghouse dust comprising iron oxide and at least 1% zinc by weight. In someaspects, the solid composition does not include a non-carbonaceous ironreducing agent. Non-limiting examples of non-carbonaceous iron reducingagents include ferrous chloride and ferrous sulfate. In someembodiments, the solid composition carbon source comprises greater than90% carbon by weight, preferably greater than 80% carbon. In someaspects, the solid composition carbon source is selected from the groupconsisting of anthracite, graphite, coal, coke, petcoke, coal tar pitch,tar, molasses, decanter sludge, petrochemical waste coke, aluminumsmelter spent pot lining or combinations thereof. In some aspects, thebag house dust iron oxide is iron (II) oxide (FeO), iron (III) oxide(Fe₂O₃), iron (HMI) oxide (Fe₃O₄, Fe₅O₆, Fe₅O₇), or mixtures thereof,preferably Fe₂O₃. In some embodiments, the bag house dust zinc is zincoxide (ZnO), or any other zinc-containing oxide, zinc ferrite, ormixtures thereof. In some aspects, the solid composition comprises 0 to15% of an additive. In some aspects, die additive is selected from thegroup consisting of lime, calcium chloride, silica, limestone, clay,iron and/or steel grindings, iron and/or steel borings, iron and/orsteel turnings, or combinations thereof. In some embodiments, the baghouse dust comprises greater than 30% by weight iron oxide. In furtherembodiments, the bag house dust comprises from greater than 0 to 70% byweight iron oxide. Some aspects of the disclosure are directed towardsmaking a solid composition in the form of a briquette or pellet.

In some aspects, a briquette or pellet adapted for use as a recycledfeed stock in electric arc and/or basic oxygen furnaces is provided, thebriquette or pellet comprising 60 to 90% by weight of a bag house dustcomprising iron oxide and zinc, 3 to 20% by weight of a carbon source,and 0 to 15% by weight additive. In some aspects, the briquette orpellet does not include a non-carbonaceous iron reducing agent.Non-limiting examples of non-carbonaceous iron reducing agents includeferrous chloride and ferrous sulfate. In some embodiments, the briquetteor pellet carbon source comprises greater than 90% carbon by weight,preferably greater than 80% carbon. In some aspects, the briquette orpellet carbon source is selected from the group consisting ofanthracite, graphite, coal, coke, petcoke, coal tar pitch, tar,molasses, decanter stodge, or combinations thereof. In some aspects, thebriquette or pellet bag house dust iron oxide is iron (II) oxide (FeO),iron (III) oxide (Fe₂O₃), iron (II,III) oxide (Fe₃O₄, Fe₅O₆, Fe₅O₇), ormixtures thereof, preferably Fe₂O₃. lit some embodiments, the briquetteor pellet bag house dust zinc is zinc oxide (ZnO), or any otherzinc-containing oxide, zinc ferrite, or mixtures thereof. In someaspects, the briquette or pellet additive is selected from the groupconsisting of lime, calcium chloride, silica, limestone, clay, ironand/or steel grindings, iron and/or steel borings, iron and/or steelturnings, or combinations thereof. In some embodiments, the bag housedust comprises greater than 30% by weight iron oxide. In furtherembodiments, the bag house dust comprises 30 to 70% by weight ironoxide. Some aspects of the disclosure are directed towards making abriquette or pellet adapted for use as a recycled feed stock in electricarc and/or basic oxygen furnaces.

In some aspects of the disclosure, a steel product selected front thegroup of flat products and long products is provided, the steel productcomprising <99% by weight unrecycled iron, >1% by weight iron derivedfrom recycled bag house dust in the form of a briquette or pellet; therecycled bag house dust comprising <99% by weight iron oxide, >1% byweight zinc, a carbon source. In some embodiments, the recycled baghouse dust comprises 0-15% of an additive. In some aspects, the recycledbag house dust does not include a non-carbonaceous iron reducing agent.Non-limiting examples of non-carbonaceous iron reducing agents includeferrous chloride and ferrous sulfate. In some embodiments, the recycledbag house dust carbon source is selected from the group consisting ofanthracite, graphite, coal, coke, petcoke, coal tar pitch, tar,molasses, decanter sludge, or combinations thereof. In some aspects, therecycled bag house dust iron oxide is iron (II) oxide (FeO), iron (III)oxide (Fe₂O₃, iron (II,III) oxide (Fe₃O₄, Fe₅O₆, Fe₅O₇), or mixturesthereof preferably Fe₂O₃. In some embodiments, the recycled bag housedust zinc is zinc oxide (ZnO), or any other zinc-containing oxide, zincferrite, or mixtures thereof.

Some aspects of the disclosure are directed towards a method of making asteel product comprising die steps of obtaining a solid composition inthe form of a briquette or pellet, introducing the solid compositioninto an electric arc furnace or basic oxygen furnace, operating saidelectric arc furnace or basic oxygen furnace to produce molten steel,and processing the molten steel from the electric arc furnace or basicoxygen furnace into a steel product. In some aspects, the solidcomposition comprises a carbon source and a baghouse dust comprisingiron oxide and at least 1% zinc by weight. In further embodiments, thesolid composition comprises 60 to 90% by weight of a bag house dustcomprising iron oxide and zinc, 3 to 20% by weight of a carbon source,and from 0 or greater than 0 to 15% by weight additive. In someembodiments, the iron oxide comprises 30 to 70% by weight of the baghouse dust. Additives include lime, calcium chloride, silica, limestone,clay, iron and/or steel grindings, iron and/or steel borings, ironand/or steel turnings, and the like. In some aspects, the briquette orpellet does not include a non-carbonaceous iron reducing agent.Non-limiting examples of non-carbonaceous iron reducing agents includeferrous chloride and ferrous sulfate. In some embodiments, the carbonsource is selected from the group consisting of anthracite, graphite,coal, coke, petcoke, coal tar pitch, tar, molasses, decanter sludge, orcombinations thereof. In some aspects, the iron oxide is iron (II) oxide(FeO), iron (III) oxide (Fe₂O₃). iron (KIM oxide (Fe₃O₄, Fe₅O₆, Fe₅O₇ ormixtures thereof preferably Fe₂O₃. In some embodiments, the zinc is zincoxide (ZnO), or any other zinc-containing oxide, zinc ferrite, ormixtures thereof.

The term “coupled” is defined as connected, although not necessarilydirectly, and not necessarily mechanically.

The terms “a” and “an” are defined as one or more unless this disclosureexplicitly requires otherwise.

The term “substantially” is defined as being largely but not necessarilywholly what is specified (and include wholly what is specified) asunderstood by one of ordinary' skill in the art, in any disclosedembodiment, the term “substantially” may be substituted with “within [apercentage] of” what is specified, where the percentage includes 0.1, 1,5, and 10 percent.

The terms “comprise” (and any form of comprise, such as “comprises” and“comprising”), “have” (and any form of have, such as “has” and“having”), “include” (and any form of include, such as “includes” and“including”) and “contain” (and any form of contain, such as “contains”and “containing”) are open-ended linking verbs. As a result, a briquettethat “comprises,” “has,” “includes” or “contains” one or more elementspossesses those one or more elements, but is not limited to possessingonly those one or more elements. Likewise, an element of a system orcomposition that “comprises,” “has,” “includes” or “contains” one ormore features possesses those one or more features, but is hot limitedto possessing only those one or more features.

In the context of the present invention, seventeen embodiments are nowdescribed. Embodiment 1 is a solid composition adapted for use as a feedstock in steel making furnaces. The solid composition contains abaghouse dust containing iron oxide and at least 1% zinc by weight; anda carbon source, wherein said solid composition is in the form of abriquette or pellet. Embodiment 2 is the solid composition of embodiment1, wherein the product does not contain either or both of ferrouschloride and ferrous sulfate amount that alters the properties of thecomposition as a feed stock in steel making furnaces. Embodiment 3 isthe solid composition of embodiments 1 or 2, wherein the carbon sourcecontains greater than 50% carbon by weight. Embodiment 4 is the solidcomposition of either of embodiments 1 to 3, wherein the carbon sourceis selected front the group consisting of anthracite, graphite, coal,coke, petcoke, coal tar pitch, tar, tar, molasses, decanter sludge, andcombinations thereof. Embodiment 5 is the solid composition of either ofembodiments 1 to 4, wherein the iron oxide is iron (II) oxide (FeO),iron (III) oxide (Fe₂O₃), iron (0,01) oxide (Fe₃O₄, Fe₅O₆, Fe₅O₇), ormixtures thereof preferably Fe₂O₃. Embodiment 6 is the solid compositionof either of embodiments 1 to 5, wherein the zinc is zinc oxide (ZnO),or any other zinc containing oxide, zinc ferrite, or mixtures thereof.Embodiment 7 is the solid composition of either of embodiments 1 to 6,further containing from greater than 0% up to 15% by weight of anadditive. Embodiment 8 is the solid composition of embodiment 6, whereinthe additive is selected from the group consisting of lime, calciumchloride, silica, limestone, clay, iron and/or steel grindings, ironand/or steel borings, iron and/or steel turnings, and combinationsthereof. Embodiment 9 is the solid composition of either of embodiment 1to 8, wherein the baghouse dust contains greater than 30% iron oxide byweight. Embodiment 10 is the solid composition of either of embodiment 1to 9, wherein the baghouse dost contains 30% to 70% iron oxide byweight.

Embodiment 11 is a briquette or pellet adapted for use as a recycledfeed stock in electric arc and/or basic oxygen furnaces, the briquetteor pellet containing: 60 to 90% by weight of a bag house dust containingiron oxide and zinc, wherein the iron oxide contains 30 to 70% by weightof the bag house dust; 3 to 20% by weight of a carbon source; and 0 to15% by weight additive. Embodiment 12 is the briquette or pellet ofembodiment 11, wherein the product does not contain either or both offerrous chloride and ferrous sulfate. Embodiment 13 is the briquette orpellet of embodiment 11 or 12, wherein the carbon source containsgreater than 50% carbon by weight. Embodiment 14 is the briquette orpellet of either of embodiment 11 to 13 wherein the carbon source isselected from the group consisting of anthracite, graphite, coal, coke,petcoke, coal tar pitch, tar, tar, molasses, decanter sludge, andcombinations thereof. Embodiment 15 is the briquette or pellet of eitherof embodiment 11 to 14, wherein the additive is selected from ‘the groupconsisting of lime, calcium chloride, silica, limestone, clay, ironand/or steel grindings, iron and/or steel borings, iron and/or steelturnings, and combinations thereof. Embodiment 16 is the briquette orpellet of either of embodiment 11 to 15, wherein the iron oxide is iron(II) oxide (FeO), iron (III) oxide (Fe₂O₃), iron (II,III) oxide (Fe₃O₄,Fe₅O₆, Fe₅O₇), or mixtures thereof preferably Fe₂O₃. Embodiment 17 isthe briquette or pellet of either, of embodiment 11 to 16, wherein thezinc is zinc oxide (ZnO), or any other zinc-containing oxide, zincferrite, or mixtures thereof.

The feature or features of one embodiment may be applied to otherembodiments, even though not described or illustrated, unless expresslyprohibited by this disclosure or the nature of the embodiments. Anyembodiment of any of the disclosed container assemblies and compositionscan consist of or consist essentially of rather thancomprise/include/contain/have, any of the described elements and/orfeatures and/or steps. Thus, in any of the claims, the term “consistingof or “consisting essentially of can be substituted for any of theopen-ended linking verbs recited above, in order to change the scope ofa given claim from what it would otherwise be using the open-endedlinking verb. Details associated with the embodiments described aboveand others are presented below.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graph of exhaust gas composition and furnace temperatureduring reduction as per Example 1.

FIG. 2 shows the XRD pattern of an unreduced briquette according toExample 1.

FIG. 3 shows the XRD pattern of a reduced briquette according to Example1.

DETAILED DESCRIPTION

Various features and advantageous details are explained more fully withreference to the non-limiting embodiments that are illustrated in theaccompanying drawings and detailed in the following description. Itshould be understood, however, that the detailed description and thespecific examples, while indicating embodiments of the invention, aregiven by way of illustration only, and not by way of limitation. Varioussubstitutions, modifications, additions, and or rearrangements willbecome apparent to those of ordinary skill in the art from thisdisclosure.

In the following description, numerous specific details are provided toprovide a thorough understanding of the disclosed embodiments. One ofordinary skill in the relevant art will recognize, however, that theinvention may be practiced without one or more of the specific details,or with other methods, components, materials, and so forth. In otherinstances, well-known structures, materials, or operations are not shownor described in detail to avoid obscuring aspects of the invention.

The present disclosure provides methods and compositions that make useof the steel-making waste by-product, bag house dust. The bag house dustcontains valuable materials such as iron and zinc, primarily in the formof oxides. High oxide content in the bag house dust oxide precludesdirect use of bag house dust in industrial steel furnaces. In themethods and compositions disclosed herein, the bag house dust iscombined with a carbon source and optionally an additive, and moldedinto briquettes or pellets. Without wishing to be bound by theory, thecarbon source is believed to act as an in situ reducing agent thatassists in transformation of metal oxides to useful metals. Thebriquettes or pellets may be employed as a source of iron, zinc, and/orcarbon in iron, zinc, or steelmaking processes.

The bag house dust is mixed with, a carbon source and molded intobriquettes or pellets. The carbon source carbon source may beanthracite, graphite, coal, coke, petcoke, coal tar pitch, tar,molasses, decanter sludge, or combinations thereof. In some aspects, thecarbon source and bag house dust are combined in a weight ratio rangingfrom 0.03:1 to 0.18:1, with carbon as the major weight constituent ofthe carbon source. In one embodiment, the briquettes or pellets comprisea 0.06:1 weight ratio of carbon source to bag house dust.

One or more additives may optionally be included in the pellets orbriquettes, including lime, calcium chloride, silica, limestone, day,iron and/or steel grindings, iron and/or steel borings, iron and/orsteel turnings, and the like. The pellets or briquettes may include anoptional binder. The pellets or briquettes may include one or morenon-carbonaceous reducing agents. In preferred embodiments,non-carbonaceous reducing agents are excluded from the pellets orbriquettes.

The pellets or briquettes may be employed in a steelmaking processwherein the bag house dust iron oxide is used as an iron source for theproduction of steel. The pellets or briquettes may be combined withrecycled iron or steel, unrecycled iron, or a metal ore.

In a briquette or pellet-making process, bag house dust is combined witha carbon source and shaped into briquettes or pellets. The bag housedust, carbon source, optional additive, and optional binder are combinedin a mixing apparatus. In some embodiments, the carbon source acts as abinder. The binder, if added, will be sufficient to bind together thecarbon source and the BHD to be formed into briquettes via the chosenprocessing technique. Typically, the binder will be present in an amountof from 1 to 20% by weight of the mixture of BHD, carbon source and thebinder. Preferred binders include hydrocarbon binders such as, e.g.,corn starch, cellulose, and the like. Water may be optionally added tothe mixture to create a slurry.

The relative amounts of bag house dust, carbon source, and optionalcomponents (additive, binder, and water) may be adjusted in order toimprove the adherence of the mixture and/or the strength of thebriquette or pellet product. The mixture may be mixed at roomtemperature, or it may be subjected to heating conditions.

The mixture is formed into briquettes or pellets using any molding orshaping method known in the art. Exemplary methods include extrusion andpelletizing. The shaped briquette or pellet may be further coated withadditional bag house dust mixture and subsequently molded or shaped.

The shaped briquette or pellet may be heated in an oven. The oven may beused to remove water, increase binding, and/or cause at least a portionof the metal oxide content to be reduced. The oven may be provided witha stream of oxygen or an oxygen-containing gas or in inert atmospheresuch as Ar and N. The briquettes or pellets may be used immediately ormay be aged prior to using. Aging of the briquettes or pellets may beaccomplished at ambient temperature or under elevated temperature.

The briquettes or pellets may be used in iron or steel-making furnaces.The briquettes or pellets may be used in other processes, for example,the briquettes or pellets may be used in a Midrex and HYL processes orany other reduction technology whereby the iron oxide is reduced in theabsence of melting. The briquettes or pellets may be used as anaggregate and added to concrete. The briquettes or pellets may be usedto enhance zinc content in zinc distillation or extraction methods. Therecycling of bag house dust may provide financially advantageousenvironmental protection credits for waste reduction and/or recycling ofiron and zinc oxides.

Example 1 Analysis of Self-Reducing Baghouse Dust (BHD) Briquettes

Baghouse dust (BHD) briquettes containing carbon as a reductant inbriquettes containing carbon as a reductant in a 1.6:1 molar ratio ofcarbon to Fe₂O₃ The BHD briquettes were prepared by mixing 10 wt %carbon with 90 wt % BHD along with water. The wet mixture was thenpressed into briquettes with a roller press cold briquetting machine.The BHD was provided by SABIC, and was obtained from an electric arcfurnace. The chemical composition of an exemplary, non-limiting BHDanalyzed by X-ray fluorescence spectrometry (XRF) used in accordancewith the present invention is provided below in Table 1:

TABLE 1 Element Average weight (%) Aluminum (Al) 0.17 Calcium (Ca) 5.79Iron (Fe) 29.44 Magnesium (Mg) 2.5 Manganese (Mn) 1.52 Lead (Pb) 1.8Silicon (Si) 1.31 Zinc (Zn) 18.78 Potassium (K) 3.24 Sodium (Na) 0.88Chloride (Cl) 2.25 Sulfur (S) 0.46 Phosphorus (P) 0.13 Copper (Cu) 0.13

The briquettes of Example 1 were subjected to reduction at 1100° C. andanalyzed. Analysis of the as-received and reduced briquettes wasperformed by x-ray diffraction (XRD) for phase identification, and x-rayfluorescence (XRF) spectrometry to determine approximate elementalcomposition. The nominal compositions of the reduced BHD briquettes issummarized in the Table 2 below:

TABLE 2 Composition of reduced BHD briquettes (All constituents above 1%listed unless otherwise noted.) Element Concentration (wt. %) Zn  5-20Ca  8-15 Fe 29-37 Pb 1-3 Mg 1-2 Al <1 Mn 1-2 Si 2-3 Na 2-3 K 1-2

Reduction of a sample briquette was carried out in a vertical tubefurnace under flowing argon gas (flow rate of 150 mL/min). One briquettewas weighed, and then suspended (using Kanthal wire) at the top of thefurnace while the furnace was heating up. The furnace was taken fromroom temperature to 1100° C. at a rate of 5° C. per minute, where it washeld for one hour, before being cooled to room temperature also at arate of 5° C. per minute. Upon reaching 1100° C., the briquette waslowered into the hot zone of the furnace, and the exhaust gasses weredirected to an infrared gas analyzer, which recorded the concentrationsof CO, CO₂, CH₄, H₂, and O₂. After the furnace had fully cooled down,the briquette was removed from the furnace and weighed again.

XRD patterns were analyzed by using the QualX software package (See A.Altomare, N. Corriero, C. Cuocci, A. Falcicchio, A. Moliterni, and R.Rizzi, “QUALX2.0: a qualitative phase analysis software using the freelyavailable database POW_COD,” J. Appl. Crystallogr., vol. 48, no. 2, pp.598-603, April 2015). The patterns were filtered to remove the broadcarbon peak present around 20=25°, and major peaks were identified fromthe filtered pattern. The search-match database was restricted toelements listed in Table 1, in addition to carbon and oxygen in order toaccount for oxides and carbides that may have been present. The phasesthat best accounted for the peaks were selected manually.

Results

Data gathered from the infrared gas analyzer is plotted in FIG. 1. Itshows a sudden increase in the CO generation rate, which peaks afterapproximately 10 minutes, then decays. Similar peaks are seen in theconcentration of CO₂ and H₂. The presence of hydrogen gas indicates thatthe reductant is not pure carbon, but likely a pulverized coal. The longdecay time is due to the residence time of the exhaust gasses in thefurnace (caused by the low flow rate, 150 mL/minute); note that the rateof decay does not significantly change after the furnace begins to coolafter the 1 hour dwell at 1100° C. Reduction was likely completedshortly after the peak in CO concentration was reached.

The data suggests that the rate of reduction is quite fast. The infrared(IR) spectrometer data is particularly useful for determining the totalamount of CO, CO₂, and H₂ produced by integration of the curves.

The mass loss of the briquette was significant (initial mass=13.7 g,final=9.2 g). The inside surface of the furnace tube was also coatedwith a gray powder, which was analyzed by scanning electron microscope(SEM) and Energy Dispersive X-ray Spectroscopy (EDS) and found tozinc-contain primarily zinc. The XRF results (Table 3, which shows theapproximate ratios of Ca, Fe, and Zn, normalized to 100%) show an almostcomplete loss of zinc in the final product.

TABLES 3a and 3b XRF analysis of samples before reduction (top) andafter reduction (bottom) Element Concentration (wt. %) Table 3a Ca 21 Fe65 Zn 14 Table 3b Ca 27 Fe 73 Zn <1

XRD of an unreduced ground briquette shows in FIG. 2 that the maincrystalline phases are magnetite (Fe₃O₄, phase P.1 in FIG. 2), wustite(FeO, phase P.2), lime (CaO, phase P.3), zinc oxide (ZnO, phase P.4),and sodium and potassium oxides (Na₂O and K₂O, phases P.6 and P.5,respectively). The other constituents shown in the chemical analysis arenot visible over the background, either because they are not present insignificant enough concentrations or because they are not crystallineenough to generate a strong x-ray signal.

XRD on the reduced briquette as shown in FIG. 3 show a different set ofpeaks. First two phases of metallic iron are present, ferrite (phase P.1in FIG. 3) and austenite (phase P.3). Lime (CaO, phase P.2) is stillpresent, but peaks corresponding to a dicalcium silicate (Ca₂SiO₃, phaseP.4) are now present. Zinc oxide is not present in the XRD pattern, asexpected given the XRF data in Table 2.

This suggests that the briquette has been fully reduced by the reductantin about 1 hour or less at 1100° C. The presence of austenite is likelydue to the presence of significant amounts of manganese. If allmanganese was reduced as well, the resulting iron should contain ˜5weight percent manganese given the composition in Table 1. Manganese isan ausenite stabilizer as can be seen from, e.g., the phase diagram inFIG. 4 of the ASM Handbook, Volume 3, Alloy Phase Diagrams (1998). It isbelieved, without being bound to any theory, that the presence ofdicalcium silicate is likely due to interactions between the CaO andSiO₂, as silica was not detected in the unreduced sample's XRD patternbecause it was either not present in sufficient quantities or wasamorphous.

From the data, it can be concluded that reduction was rapid at thetested furnace temperature of 1100° C., resulting in complete reductionof the iron and near-complete removal of zinc by reduction of zinc oxideto metallic zinc, that evaporated out of the briquette.

Example 2

The BHD of Example 1 having the composition shown in Table 1 aboveprocess was premixed with anthracite as a carbon source according to theprocedure and ratios described in Example 1 above and shaped intopellets/briquettes using the method of Example 1.

Experiments were conducted to evaluate the use of BHD and theaforementioned carbon briquettes in the EAF. Different experiments wereconducted with varying temperature and time. The summary of experimentalresult shown in table −1

Steps for conducting the experiment of Example 2 are described below inTable 3 with reference to Table 4:

TABLE 3 Method Using Box Furnace 1. Preheat the furnace to requiredtemperature while empty crucible is inside 2. Alumina crucible was usedto conduct experiment. 3. Open the furnace and put the sample 4. Closethe furnace 5. Hold for the indicated time 6. Shut down the furnace,remove the sample and quench in water.

TABLE 4 Experimental results Temp. Time Mass Mass Fe Metallic SampleMaterials (° C.) (min) before (g) after (g) Total (%) Fe % Metallization% A1 90% BHD + 1400 10 161.4 133.8 82.4 64.7 79.02 B1 10% Carbon 138.8127.3 82.46 66.4 81.76 C1 158.2 118 82.42 65.6 80.19 A2 90% BHD + 140015 158.5 127 82.38 65.6 80.03 B2 10% Carbon 160.9 104.3 82.47 65.6 80.69AA1 90% BHD + 1200 10 163 127.9 83.1 63.9 77.35 BB1 10% Carbon 160.9137.4 82.9 63 76.55 CC1 163.3 136.9 82.4 63.1 76.65 AA2 90% BHD + 120015 142.1 125.9 82.7 65.9 79.79 BB2 10% Carbon 155.2 125.2 83.05 66.2379.83 CC2 162.4 131.1 82.47 65.7 79.69

The results in Table 4 show that the four set of experiments conductedwith varying temperature (1200° C. and 1400° C.) and holding time 10 and15 min) result show that acceptable amounts of reduction occur in allcases (76.55 to 80.69% reduction).

At 1200° C. and 10 min holding time metallization varies from 76.55% to77.35% whereas with 15 min holding time metallization varies from 79.69%to 79.83%.

In case of 1400° C. and 10 min holding time metallization varies from79.02% to 81.76% whereas with 15 min holding time metallization variesfrom 80.03% to 80.69%.

The claims are not to be interpreted as including means-plus- orstep-plus-function limitations, unless such a limitation is explicitlyrecited in a given claim using the phrase(s) “means for” or “step for”respectively.

1. A solid composition adapted for use as a feed stock in steel makingfurnaces comprising; (i) a baghouse dust comprising iron oxide and atleast 1% zinc by weight; and (ii) a carbon source; wherein said solidcomposition is in the form of a briquette or pellet
 2. The solidcomposition of claim 1, wherein the product does not comprise either orboth of ferrous chloride and ferrous sulfate amount that alters theproperties of the composition as a feed stock in steel making furnaces.3. The solid composition of claim 1, wherein the carbon source comprisesgreater than 50% carbon by weight.
 4. The solid composition of claim 1,wherein the carbon source comprises at least one member selected fromthe group consisting of anthracite, graphite, coal, coke, petcoke, coaltar pitch, tar, tar, molasses and decanter sludge.
 5. The solidcomposition of claim 1, wherein the iron oxide is iron (II) oxide (FeO),iron (III) oxide (Fe₂O₃), iron (II,III) oxide (Fe₃O₄, Fe₅O₆, Fe₅O₇), ormixtures thereof.
 6. The solid composition of claim 1, wherein the zincis zinc oxide (ZnO), or any other zinc containing oxide, zinc ferrite,or mixtures thereof.
 7. The solid composition of claim 1, furthercomprising from greater than 0% up to 15% by weight of an additive. 8.The solid composition of claim 7, wherein the additive comprises atleast one member selected from the group consisting of lime, calciumchloride, silica, limestone, clay, iron grindings, steel grindings, ironborings, steel borings, iron turnings and steel turnings.
 9. The solidcomposition of claim 1, wherein the baghouse dust comprises greater than30% iron oxide by weight.
 10. The solid composition of claim 1, whereinthe baghouse dust comprises 30% to 70% iron oxide by weight.
 11. Abriquette or pellet adapted for use as a recycled feed stock in electricarc and/or basic oxygen furnaces, the briquette or pellet comprising;(i) 60 to 90% by weight of a bag house dust comprising iron oxide andzinc, wherein the iron oxide comprises 30 to 70% by weight of the baghouse dust; (ii) 3 to 20% by weight of a carbon source; and (iii) 0 to15% by weight additive.
 12. The briquette or pellet of claim 11, whereinthe product does not comprise either or both of ferrous chloride andferrous sulfate.
 13. The briquette or pellet of claim 11, wherein thecarbon source comprises greater than 50% carbon by weight.
 14. Thebriquette or pellet of claim 11, wherein the carbon source comprises atleast one member selected from the group consisting of anthracite,graphite, coal, coke, petcoke, coal tar pitch, tar, tar, molasses anddecanter sludge.
 15. The briquette or pellet of claim 11, wherein theadditive comprises at least one member selected from the groupconsisting of lime, calcium chloride, silica, limestone, clay, irongrindings, steel grindings, iron borings, steel borings, iron turningsand steel turnings.
 16. The briquette or pellet of claim 11, wherein theiron oxide comprises at least one member selected from the groupconsisting of iron (II) oxide (FeO), iron (III) oxide (Fe₂O₃), and iron(II,III) oxide (Fe₃O₄, Fe₅O₆, Fe₅O₇).
 17. The briquette or pellet ofclaim 11, wherein the zinc is zinc oxide (ZnO), or any otherzinc-containing oxide, zinc ferrite, or mixtures thereof.
 18. Thebriquette or pellet of claim 13, wherein the additive comprises at leastone member selected from the group consisting of lime, calcium chloride,silica, limestone, clay, iron grindings, steel grindings, iron borings,steel borings, iron turnings and steel turnings.
 19. The briquette orpellet of claim 13, wherein the iron oxide comprises at least one memberselected from the group consisting of iron (II) oxide (FeO), iron (III)oxide (Fe₂O₃), and iron (II,III) oxide (Fe₃O₄, Fe₅O₆, Fe₅O₇).
 20. Thebriquette or pellet of claim 13, wherein the zinc is zinc oxide (ZnO),or any other zinc-containing oxide, zinc ferrite, or mixtures thereof.